Dedicated breast CT is an emerging technology with less than 10 clinical prototypes worldwide. It can eliminate breast tissue superposition and provides 3D images at near-isotropic spatial resolution. Earlier generations of breast CT used detectors that were suboptimal in terms of inactive region near the chest wall (chest-wall dead space), limited resolution and frame rate, and higher electronic (system) noise. Newer detectors such as the one proposed in this research reduces electronic noise by a factor of 20-30, increases the spatial resolution by a factor of at least 2, and has chest-wall dead space similar to mammography that would enable excellent posterior coverage. However, these detectors are smaller in size and it is a challenge to cover large breasts. Hence, in this research we propose to design, develop and integrate the high-resolution, low-noise detector in a laterally-shifted imaging geometry that would cover the largest breast. The three major concerns regarding breast CT are, chest-wall and axillary coverage, ability to visualize microcalcification clusters, and the ability to provide diagnostic quality images at radiation dose equivalent to screening mammography. We hypothesize that the proposed technological approach will address all of these concerns. Chest-wall coverage will be improved with the proposed detector due to its chest-wall dead space of 3 mm compared to 34.2 mm used in previous clinical studies. With the proposed detector, the combination of smaller pixel size (0.15 mm compared to 0.388 mm detector pixel size in previous generations) and lower electronic noise (~200 electrons compared to ~6,000 electrons in previous generations) will allow low-dose high-resolution imaging. Additionally, it allows for completing the scan in less than 4 seconds compared to at least 10 seconds in previous generations, reducing the possibility of patient motion. The study will also integrate a beam shaping filter that further reduces the radiation dose and will incorporate scatter-reduction and residual scatter-correction methods that will improve the quantitative accuracy. This would allow for more reliable use of the Hounsfield scale (CT numbers) that can allow for better discrimination between benign and malignant findings. The research is broadly organized in three phases. In the first phase, all aspect of the design will be verified and validated on a bench-top platform to determine the best choice of parameters. In the second phase, these results will be used to design, modify and integrate the approach to a clinical prototype breast CT system. In the third phase, we will conduct a clinical feasibility stuy that will recruit BIRADS 4 or 5 subjects with microcalcifications to determine if the implemented technological advancements translate to improved visualization of microcalcifications and better discrimination between benign and malignant calcification-based lesions. Thus, the proposed research will provide an innovative design concept for unprecedented improvements that will enable imaging without physical compression of the breast and at radiation dose approximately similar to screening mammography.